The form that sleep problems take for the great majority of sleep sufferers is called insomnia—the inability to fall asleep, stay asleep, or to sleep well. It is safe to say that almost all of us suffer from it in one form or another at some time. Some people are inclined to suffer insomnia during times of stress, much as other people might suffer headaches or indigestion. A troubled marriage, a sick child, or an unrewarding job can often disrupt people’s sleep. However, we tend to be troubled by the unusual, the uncommon, the unfamiliar things that occur in our lives—and so, passing changes in our sleep patterns may alarm us.

The effects of insomnia are predictable. If sleep is reduced to five hours per night, even if only for two nights, alertness, vigilance, and creativity suffer. Sleepy people are less ambitious and less productive. Their performance on cognitive tasks involving memory, learning logical reasoning, arithmetic calculations, pattern recognition, complex verbal processing, and decision-making has been shown to be impaired by sleep loss. Still, most of us will find that with the passing of the external event causing the insomnia or with some simple changes in habit, regular sleep returns. However, for some, the solution is less simple.

Insomnia, then, is a symptom, not an illness. It is a condition where people frequently cannot get to sleep for as much as an hour after they turn in, awaken frequently during the night, or waken early and are unable to go back to sleep. Long-term insomnia, however, can be serious enough to radically degrade the quality of the sufferer’s life.

Researchers speculate that the body produces a sleep-inducing chemical, as yet unidentified, that accumulates while we are awake. As the chemical builds up over a period of time, we become sleepier and sleepier, and we eventually doze off. Our biological clock in our brains control the time at which we go to sleep and the time at which we awake.

However, a number of conditions—both internal and external—can cause this process to go awry. For example, pregnancy brings on insomnia. Women are more likely to suffer from insomnia than men by a ratio of 30 to 40 percent. In addition, appetite suppressants suppress sleep, and smokers take longer to fall asleep and sleep more lightly than those who do not smoke. Shift workers have more trouble with insomnia than others with 40 to 80 percent having difficulty with sleep. Little wonder the average shift worker sleeps between two and four hours less each night than the day worker.